1. Field of the Invention
The present invention relates to an image pickup element having a photoelectric conversion function and an image pickup apparatus including the same.
2. Description of the Background Art
Conventionally, image pickup elements having photoelectric conversion function are used as image sensors since they can be arranged one or two dimensionally to obtain image signals, and they find wide application such as video cameras, copy machines, facsimile machines and the like.
Among such image pickup elements, there are CMOS sensors manufactured through processes compatible with production of MOS (Metal Oxide Semiconductor) transistors of high integration density.
In recent years, particularly reduction of image pickup elements in size has been required, and various schemes for achieving a higher integration have been proposed.
In Japanese Patent Laying-Open Nos. 2001-24948 and 2002-50752, schemes for achieving a higher integration by reducing the number of components constituting one image pickup element corresponding to one pixel have been proposed. Specifically, the number of transistors per one pixel is reduced by arranging transistors and the like to be shared by a plurality of pixels.
The publications above disclose the schemes for improving the integration level by reducing the number of transistors per one pixel by arranging transistors to be shared by a plurality of pixels. However, since the number of components for each pixel is not uniform, layout patterns are not uniform among the pixels.
In this regard, there has been such a problem that so-called fixed pattern noises (hereinafter also referred to as FPN) occur greatly with nonuniform layout patterns, which prevent an image detection of high resolution and high image quality.